The present invention relates to document handling systems and, more particularly, to document handling systems in which information must be imaged from a document being transported automatically through a machine.
In document scanning devices, such as character recognition systems or microfiche, a good deal of time and effort can be wasted if it is necessary to locate each document by hand in a positon which will allow the information on the document to be read or copied. Either system usually requires segments of a document to be optically scanned and the difference in reflectance converted into an electrical signal. When a character recognition system is used the signal is converted into binary numbers that indicate whether part of a character or background is contained at various locations on the document. In a microfiche system, the optical image of the document is stored on film. In either case it is necessary for either the scan to move in a controlled fashion or for the document to do so. In the equipment of the present invention it is the document which is moved. However, in order to preserve the information carried by the document, its movement through the machine must be relatively slow. The throughput of prior systems has been limited to the maximum read rate of the system. Since the read station, especially in a character recognition system, can be several feet in length, such machines may be very slow indeed. When a document scanning device operates at a slow speed it is difficult to stack the scanned documents on a horizontal surface. Therefore, complicated inclined stack trays of relatively minor height have to be used. The low capacity of the stack trays requires the frequent emptying of them, thus further slowing the document reading operation.
Moreover, prior types of document elevators which position the documents for feeding into a scanning device require guides for accurately aligning for the document before it is fed into the machine in order to make sure that it is not skewed. Such document transport equipment has not heretofore had the capability of automatically deskewing or aligning the documents during their movement therethrough. Time is wasted therefore in manually aligning and checking the alignment of documents being stacked to be fed through the machine. Also, document elevators that provide edge registration, usually require the drive to be canted to force the document against a guiding edge. This tends to skew documents with high aspect ratios, such as checks.
The belt-type document carriers of the prior art generally include several narrow opposing belts on each side of the document in order to support it across its width. However, with this type of arrangement there is a tendency for the edges of the document to be caught by one of these belts, thus causing a paper jam with the attendant lost in operating time and perhaps damage to the document.